Lamp support arm



FIG. 1 is a side elevation view of the lamp support arm in accordance with my design, illustrating a possible environment for the support arm;

FIG. 2 is a side elevation view of the lamp support arm in accordance with my design;

FIG. 3 is a top plan view of the lamp support arm in accordance with my design;

FIG. 4 is a bottom plan view of the lamp support arm in accordance with my design;

FIG. 5 is a rear elevation view of the lamp support arm in accordance with my design; and,

FIG. 6 is a front elevation view of the lamp support arm in accordance with my design.

The right and left elevation views are mirror images. The broken lines showing environmental structure are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for the lamp support arm, as shown and described. 